C. diff Risk


Oral Bioavailability


Approximate Cost

IV-$9/d PO-$1/d



500 mg/dose PO x 1 dose on Day 1
then 250 mg/dose PO q24h on Days 2-5

500 mg/dose IV q24h for 2 days then switch to oral therapy


Dose adjustment not necessary.
Use with caution if CrCl<10mL/minute.

General Information

Common Usage

Community acquired pneumonia, Pertussis, upper respiratory tract infections, Chlamydial infections, mycobacterial infections

Drug Monitoring

Monitor QTc in patients with increased risk.

Adverse Effects

Prolongation of QTc interval.
One study suggested that there is 3-8 fold risk of pyloric stenosis with use of azithromycin in neonates. Therefore clinicians need to weigh benefits and risks when considering whether to use azithromycin in young infants.

Major Interactions

While less risk of interaction compared to other macrolides, several potential CYP450 interactions may occur; consult a pharmacist for for more details.

Avoid concurrent use with other drugs that prolong QTc


Antimicrobial class: Macrolide

Route of Elimination: 50% excreted unchanged in bile.

6-14% excreted unchanged in urine.

Average serum half life: Pediatrics: 54.5 hours